New Procedure for Estimating Cable Force in Cable-stayed Bridge

Abstract

In structural health monitoring of the cable-stayed bridges, estimation procedure for the cable tension influences the accuracy of monitoring system. Although some formulas are used in many monitoring systems, the results from these formulas are not accurate because they neglect the initial deflection, the natural frequency changing, and the initial curvature shortening of an oscillating cable. This paper presents a new estimation procedure that considers these neglected effects in the existing formulas and achieves the modified accuracy in estimating the tension force in the cable. Considering the initial deflection of the cable at the static status derives a clear explanation about the natural frequency changing for the change of the slenderness ratio of the cable. And by considering the stretching force induced by the initial curvature shortening, the additional forces acting on the supports of the cable conservatively are also investigated. In this paper, the concept of total tension force is proposed to increase the accuracy in tension force estimation for the cable. The re-estimation for the cable-stayed Alamillo Bridge, Spain shows that the new procedure estimates tension force of the cables more accurately and that this can be used as an alternative procedure in the structural health monitoring system.